2)18F-FDG PET/CT protocol: GE Discovery Elite PET/CT scanner was used in multicenter trials with the same protocol. Patients were instructed to fast for at least 6 hours before 18F-FDG PET/CT scan. Blood glucose level was measured before tracer was injected. Whole-body PET/CT images, generally from the top of the skull to mid-thigh, were acquired 50~70 min after intravenous injection of 18F-FDG at the dose of 0.08~0.10 mCi per kilograms of body weight. Patients were asked to void their bladder immediately before scanning to minimize the presence of the tracer in the urinary tract. PET data were acquired and reconstructed using SharpIR+ VUE Point HD+TOF, 2min/bed. The PET data were attenuation corrected (AC) by the integrated CTAC technology. CT data were acquired in breath-hold with 120 kV, 30-210 mA modulated by GE SmartmA technique with a noise index of 25; with slice thickness 3.75 mm, slice interval 3.27 mm, pitch 1.375, matrix size 512×512 and scan FOV 50cm.